The wood thrush makes its nest in woodlands in the northern and eastern united states. as patches of woods become smaller, increasing numbers of wood thrush nests have eggs laid in them by the brown-headed cowbird. cowbirds live in open fields and are nest parasites; the female cowbird flies up to an unattended nest, quickly lays an egg in another bird's nest, and leaves the host parents to raise their "adopted" young. wood thrushes are decreasing in numbers because